Valve for hydraulic control systems



, H. c.-.rR1cH 'VALVE iFOR HYDRAULIC CONTROL SYSTEMS Agg, 7 A194s.

Filed Nov: 2*'1', 1942' EMMWWW .I vazoo mgm sure. Inaccor'dance'with f the fluid is continuously .circulated through a re- *relief valve andv vatedpressure.

, tof'thejeiect'of small particles of upoiithelnecessary control apertures. 1

' fveLvEvroR HYDRAULI'CCONTROL 'Y 1 l HenryQ'lrich, Santa Monica, Calif., assigriorV to.

*e poration'. of vIllinois' Application November 27, 1942,'

ificlaiiiis..V ,(01,251 iasyv e The present invention relates-te valve `for hy- 'draulic 'control systems andfmor'e particularly is concerned withvsystems for selectively setting vup afsou-rce of.v actuating pressure for the purpose of operating and controlling mechanicalinstrumentalities. f

In hydraulic control ysystems of the type .bestf exemplified by that employed on aircraft, apressuch for example.

sure creating instrumentality, as an engine drivenl pump, may operate continu-4 ously to supply energyin the` formlof fluid presconventional practice,`

lief valve, thus maintaining'a supply line under f elevated predetermined. pressure conditions.

Suitable control: valvesv are' employed tov supply the pressure fluid to the Various operating instrumentalities vas desired. -The continuous vpas'- sage of hydraulic-fluidi through the pump and l the Aresulting, continuous libera-` tion ofheat renders this system impractical for i smaller installations where`..heating may be vex-y `cessive.` 'Y t, l f -Sinoe utilization ofy the hydraulically controlled instrumentalities may occur only infrequently, itv has been proposed to normally by-pass the yrelief valve-tereleaserall substantial pressure in the: system, yand to close the by-pass` at times when operating pressure is necessary. Such controls, however, must necessarily be -somewhat au- 1 tomatic in character in order to obviate the nek cessity vfor specific` attention. The total available pressure capable. of being maintained between the pump and relief'fval've necessarily is substanf tally in'y excess lof `that required to operate themechanical instrumentalities. Accordingly, therefore,r itf hasbeen further proposed to provide a valve in. the".bypass line which will remain closed-during,` action ofthe mechanical instrumentalities but which will automatically ODEn Y at.y times when the mechanical movement isv comsystem resumes its normal kele- Such systems, however, are susceptiblefto gust `loads which; momentarily will disengage: the valve before the work is completed. It 'maythereforefbe necessary toy rc-engage the pleted and the valve orvhold'. it inengagedf position until the f hydraulic operation is completed; thus Idistracting thefperators.attention from other duties.

Efforts have beenmade to provide a by-pass valve g'ivifngfa predetermined time lag but in general thel operation of such devices is unreliable due foreign matter v ,-'t is animportant object of rvthe present in@ yHoof Products Company,k Chicago,y Ill. acor.-r

sepialfrquuicmiee knormally to release. the pressure but beingprovided 'with means operable at all times to close Y olf or restrict the ley-pass or return lineand maintain a predetermined restriction overa preprovision of atime lag pressure determined time period, ample for operation of the desired instrumentalities.

Another object of the present invention conv templates the .provision of a return line pressure control valvey asabove which normally permits free passagev 0f fluid but is operable-upon simple manipulation to restrict fluid flow until the me` chanical operation is completed. v

Among* other objects of the invention is they control valve, as y above, Whichfis free from the inuence of gust loads and adapted to function positively over long yperiods ,of service, substantially unaffected by thel small quantities of foreign matter existing within the ordinaryhydraulic system; the pro-l vision of-a valve, as above, which compensates in some measure for temperature conditions and f Variation in operational pressures, as well as the provisionA of a valve construction which is self-cleaning in operation and .thus free from the `necessity for frequent repair or servicing.. Other objects will be'apparent from the following specificationk and drawing, wherein Fig. l represents more or less diagrammatically a `hydraulic system embodying theprinciples of the presenty invention, and Fig. 2 is a sectional viewtaken'centrally and longitudinally through the pressure control valve vshown in Fig. 1.

The system shownin Fig. 1 embodies a' con stantlyv driven engine pump Ill capablel of supplying fluid under pressure to the conduit l2 from whence it may pass through a relief Valve i4 toa return linel and a pump inletvreservoir i8. The relief valve 'I4 is set to maintainA a predetermined/operative pressurein the line I2. For thepurpose of supplying hydraulic fluid to` Various operating instrumentalities 2U and 22 through conduits'24, the'conduits 24 are provided with check valves 26 andr operating control valves 28 through the agency of which the mechanical' instrumentalities mayr clearly'r appears from the drawing, the lcontrolv valves are of the type which provide for returninghydraulic iiuid tothe reservoir through returniinesul@ l, '1

- The' instrumentaliti'es 210 and 22 may, for exbeactuated at'will. As y ample, represent the so-called operating struts of an aircraft landing gear.

In order to prevent the generation of excessive heat at times when the instrumentalities 20 and 22 are not in operation a by-pass conduit 32 is provided with a control instrumentality 34, shown more' in detail inv Fig. 2. This pressure control valve 34 includes a generally cylindrical body portion 36 provided with an axially extending central chamber terminating at its right-hand extremity-in an outlet passageway 38 communicating with an outlet fitting 40. An inlet fitting 42 is disposed closely adjacent the passageway 38 so that the inlets and outlet are normally in communication. The left-hand-mostextremity of the cylindrical body 34 is provided with a cap 44 threadedly engaged therewith as at 46.

The cap or tting provides a bearing guideway for an axially movable rod or plunger 48 having a manually engageable operating knob 50 axially adjustable thereon, as shown. Internally ofV the cylindrical body member the rod is provided with a piston or dash-pot structure comprising a flexible cup retainer 52 resting against an enlarged or flanged portion 54 of the plunger shaft. The so-called Viiexible sealing cup is maintained in the position shown by a cup retainer 55 and a collar 58 iixed upony the plunger shaft by means of a pin 653. From the foregoing it isapparent that as the plunger is shifted to the right the i collar 58 and sealing'cap are carried with. it, the

'configuration of the flexible cup,

as shown, being such as to permit hydraulic iiuid within the chamber to passby the cup and into the space therebehind.

Egress of hydraulic iiuid along the plungerY shaft 48 is prevented by an additional flexible sealing cup 52 maintained in the position shown by a cup retainer 64 and a fixed collar 66.

The plunger extending axially beyond thev flange 54, as at 68, terminates in a piston-like extremity 10 adapted to slide axially and snugly intovthe cylindrical passageway 38 and thus substantially seal the outlet. ,A suitable shoulder 72 is provided to limit the movement of the valve piston into the passageway 38.

In accordance with the present invention, means is provided for facilitating automatic return of the parts subsequent to shifting to the last-named position. To this end helical coil spring 14 bears against the right-hand-most extremity of the valve chamber and against the ange 54. Fluid trapped behind-the sealing cup 52 is relieved through a radial passageway 18 communicating with an axial passageway T6, extending to the. right-hand-most extremity of the plunger shaft. It is important to note that in accordance ywith the present invention the rate of fluid flow lthrough the passageway 16 is determined by means of'a metering pin Ior needle 86, rigidly supported upon the housing through the agency of a threaded plug 32. vIn other words the needle or .pin Si! is rigid with the member 82, which in turn is threadedly and adjustablyy engaged with the housing or body-St, as at 84.Y

It is important to note that the needle or pin iii) is receivable within the passageway I6 when the relatively shiftable parts are moved to the right.

While the relative dimensions of the parts are such as to necessitate a more or less diagrammatic showing, it is to ybe understood` that the clearance between the needle and thev passage in which it is received is such as to permit a predetermined iiud flow for any condition of interloriginal position in `Fig. 2.

` and the plunger 48 forced inwardly against the action of spring `'i4 until the piston-like extension 10 is accommodated within the cylindrical outlet passageway 38. The distance of axial interengagement may be predetermined in accordance with the setting of the axially adjustable control handle 5I),A the locknut 5I of which affords a limiting stop upon impingement with the cap 44. Obviously this adjustment also predetermines the degree of axial interengagement between the needle 88 and the passage 16. As the shiftable parts are moved to the valve closing position, hydraulic fluid passes peripherally about the sealing cup 52 and into the chamber therebehind.` The build-upin pressure at line l2, initiated by closure of the passageway 38, together with the action of the helical spring '14, immediately tends to urge the parts toward their This tendency is, however, resisted by the incompressibility of the fluid trapped behind the movableparts and releasable through-passages I8 and 16 and through the tting 4i), In short, the rate at which the parts tend to return to normal is predetermined by the adjusted dimensions of the annular fluid passageway between the needle or pin 88 andthe passage 16 within which it is received. Accordingly, therefore, the parts occupy a time period of return to their initial position, dependent upon the width ofthe passages and the distance to which the needle is inserted. After a time lag interval, predetermined by making the adjustment of the parts as above, the parts resume the position shown and free communication between inlet 42 and outlet 48 is eiected.

From Vthe foregoing it will be apparent that upon initial actuation of the control handle 50 thep'ower line l2 vimmediately assumes an elevated pressure determined by the setting of relief valve I 4. This pressure is maintained over a predetermined length of time, suicient to complete operation of the instrumentalities 20 or 22, and is subsequently automatically released without attention by the operator.

The present invention, `as illustrated in the specific embodiment, accordingprovides a simple and effective means for setting up desired operating pressures in a continuously operating engine type of system and for automatically releasing the pressure after the desired `time interval of'operation. It is evident that the present construction is adapted to operate faithfully, with freedom from yariation. Thus it is evident that the fluid passageways providing the necessary restriction for predetermined operation are so disposed as tobe ineifect self-cleaning. Deposits of foreign matterwhich might otherwise occur are necessarilyfdislodged and the vparts tend to maintain their originally designed clearance with an accompanying reliabilityof operation.

It isobvious that various modications will occur to those skilled in the art in View of the foregoing description'without departing from the nature or spirit thereof vand the invention is accordingly not. limited to the illustrated deasif'as" y fixed adjustable flow l'regulating'means receiv-v able in the passaga adjustable manual ime'a'ns4 for moving said valve relative to 'said iiowregu-y scription ther pend'edfclaims;` y u u V1. A-time lag" pressure control valve comprising a Avalve chamber vhaving an inlet and an outlet normallyandl directly in Vcommunication through said chamber, ani outlet controlvalve said chamber havingL af'pas'sage therethroughfto *deliver fluid underpressure tothe outlet, now-regulatingfmeans receivable-in thet'p'assage, means formoving said valve relative to vsaid 'flow regulating means" to close'the outlet and permitting a predetermined rate'of flow through the passage, means {for moving said valv'e'to'fopen the outlet, and a pressure' controlled dash-pot operatively associated with said t valve and :releasable upon flow of fluid under pressure through the valve passage to 1 the outlet to retard' return ymovement ofsaid'valvefrom 'its outletfclosing position.l 2; A time' lag pressure control valve comprising` a valvejch'amber having an inlet andan outlet normally and directly `in""co'mmunicationv through Vsaid chamber', anf'outlet' control valve" in said chamber having apassa'ge therethrough todeliver iuid under pressure tothe outlet,.xed flow regulating means receivable vin the passage, means for moving said valve relative to said flowreg-ulating means tofolose the outlet and permittingja predet'erminedlrate of'low through the passage,

lmeans for moving said valve to open theoutlet,

and'v a .'pressurel controlled dash-'pot f operatively i associated' With said lvalve fand releasablel upon flow :of` iiuid under pressurev through `vthe',4 valve passage to' the outlet to retard returnmovement of said valve from its outlet closing position. l

#3.- A time lag pressure control valvefcomprisinga valve chamberhavng an inlet and an outlet vnormally fand* directly in communication through lsaid chamber, Van-'outlet control valve in saidy chamber having a passage therethrough to deliveriiiuid under'lpressure'to the outlet, fixed adjustablel flow' y regulating n ie'ansv receivable in the passage, means for moving vsaid valve rela- 'tive'. to 'said flot/'regulating'- means .to close the outlet and permitting a predetermined rate of flow through the passage, means for moving said valve to open the outlet, and a pressure controlled dash-pot operatively associated with said valve and releasable kupon iiow of fluid under pressure through the valve passage to the outlet to retard return movement of said valve from its outlet closing position. f

4. A time lag pressure control valve comprising a valve chamber having an inlet'and an'outlet normally and directly in communication through said chamber, an outlet control valve in said chamber lhaving a passage therethrough to'deliver iiuidunder pressure to the outlet, xed adjustable flowv regulating means receivable in the passage, manual means for moving said valve relative to said iiow regulating means to close the outlet and permitting a predetermined rate of ow through the passage, means for moving said valve to open the outlet, and a pressure controlled dash-pot operatively associated with said valve and releasable upon flow of fluid under pressure through the valvev passage to the outlet to retard return movement of said valve from its outlet closing position.

5. A timelag pressure control valve comprising a valve chamber having an inlet and an outlet normally and' directly in communication through said chamber, an outlet control valve in said chamber having a passage therethrough to deliver fluid under pressure to the outlet,

inA except as set fforbhj in the tap;

. determined rate of flow through the passage,

lating means toclose the outlet and permitting a'predetermied frate of flow through "the passage,means `for moving said valve to lopen the outlet, and a'pressure controlled dash-pot operatively associated with said valve andreleasable upon flow of fluid under pressure through the position. j n n 6,. A timelag pressure control valve comprising a valve chamber having an inlet and an out'-l Vlet normally and directly in communication through said chamber, an outlet controlvalve in said chamber having a passage therethrough to deliver iiuid under pressure to the outlet, -fluidvadjustable I-floW regulating means receivable in the passage, adjustable manual means for ymoving said valve relative to said flow regulating' means 'to close the outletand permitting a preautomaticv means for moving said valve to open the outlet, and a pressure controlled dashpot operatively associated with said valve and releasable uponv flow fof fluid under pressure through the valve passage to the outlet to' retard return movement of said valve from its outlet'Y closing position. y Y

, '7. A'tim'e lag'pressure control valve comprising a valve chamber having an inlet and an outlet normally and directly in communication through said chamber, an outlet control' valve in said chamber having a passage therethrough to deliver Vfluid under 'pressurefto the outlet, fluid adjustable flow regulating means receivable in the' passage, adjustable manual means for moving. said-valve relative to said ilow regulatingr means to closefthe outletfand permitting' a predetermined rate of flow through ,theY passage, spring 'meansffor moving said valve to open the outlet, and a Apressure controlled dash-pot'operatively associated with saidl valve and releasable upon iioW ofv iiuid under pressure through the valve passage to the outlet to retard return movement of vsaid valvevr from its outlet closing position.

8. A time lagpressure control valve comprising a valve chamber having an inlet and an outlet normally and directly in communication through said chamber, a valve having outlet closing means and a dash-pot piston and provided with a passage connecting the outlet and a dash- Apot chamber, riixed flow regulating means receivable in the passage, means formoving said valve relative to said flow regulating means to close the outlet and permitting a predeterminedy rate of flow through the passage, and a spring for moving said valve against retarding dash-pot .pressure to open the outlet upon flow of iiuid under pressure from the dash-pot chamber through the valve to the outlet.

9. -A time lag pressure control valve comprising a valve chamber having an inlet and an outlet normally and directly in communication through said chamber, a valve having outlet closing'means and a dash-pot piston and provided with a passage connecting the outlet and a dash-pot chamber, fixed ow regulating means receivable in the passage, adjustable manual means for moving said valve relative to said flow regulating means to close the outlet and' permitting a predetermined rate of iiow through the passage, and a spring for moving said valve against retarding dash-pot pressure to open: the outlet upon ovv of fluid under pressure from the dash-pot chamber through the valve to the outlet. l

k. A time lag pressure controlvalve comprising a valve chamber having an inlet and an.` outletvnormally and directly in communication through said chamber, a valve having voutlet `closing means and a dash-pot piston and prof,` vided with a passage connecting the outlet vand a dash-pot chamber, xed flowA regulating meansl receivable in the passage, a valve, operating plunger having an. adjustable handlefor manually `actuating said, valve relative to said 110W--v 'ing a valve chamber having an inlet and an outlet normally and directly in communication through said chamber, a valve having outlet closing meansfand a dash-pot piston and` provided `withV a passage connecting the outlet and a dash-pot chamber, a xed'rmetering pin mounted inthe valve chamber yand receivable inthe valve passage, a valve operating plunger,for

`manually actuating the said Valve relativey to said pin and permitting a predetermined rate-of ovv through the passage, and a spring to move said valveagainst retarding `dash-pot pressure t'o open the outlet upon flow of fluid' under pressure from the dash-pot chamber through theA valve passage to the outlet. Y

12. A time lag pressure control valve comprising a valve chamber'having an inlet and an outlet normally and directly in communication through said chamber, a valve having outlet closing means and a dash-pot pistonv and. provided with a passage connecting the outlet and a dash-pot chamber, a fixed metering'pinl ad.-

justably mounted in the valve chamber and receivable in the valve passage, a valve operating plunger for manually actuating the said valve relativemtosaid pin and permitting a predetermined rate of flow through the passage, and a spring to move `said valve against retarding dashpot pressure to open. the outlet upon floW of uid, under pressure from the dash-pot chamber throught/he valve passage to the outlet.

13, A timelag; pressure control valve comprising a valve chamber having an inlet `and an outlet` normally andv rdirectly in communication through said, chamber, a valve` having outlet closing means 'and a dash-pot piston and providedwitha passage connecting the outlet and a ,dash-pot chamber, a xed metering pin adjustably mounted in the valve chamber and receivable inthe valve passage,y a valve operating plunger for manually actuating the said valve relative to saidv pin land permitting a predeterrnined rate of flow thro-ugh the passage, a stop for saidA plungerfand a spring to move said valve against retarding dash-pot pressure to open the outlet upon fiow of iiuid'under pressure from the dash-pot chamber through thepvalve passage. y

14,A time lag pressure control valve comprisingavalve chamber having an inlet and an outlet normally andy .directly in communication through said chamber, `a valve having outlet closing meansY and a dash-pot piston and provided vvith a passage connecting the outlet and adash-pot chamber, axed `metering pin ad- ,justably mounted in the valve chamber and receivable:v in the valve passage, a valve operating plunger for manually actuating the said valve relative' to said pin and permitting a predeterminedv rate of flow through the passage, adjustable stop means for saidy plunger, and a spring tomove said valve against retarding dashpot pressure to open the outlet upon ow of fluid under pressure from the dash-pot chamber through the valve passage.

' HENRY C. TRICH. 

